Power assisted steering systems are provided in many vehicles, and serve to reduce the turning force that the operator of a vehicle has to apply to the steering wheel in order to steer the vehicle. The turning force required or steering depends, inter alia, on the friction between the vehicle tires and the road. This, in turn, depends on factors such as the velocity at which the vehicle is travelling and the conditions of the road surface.
Conventional power assisted steering systems are hydraulically operated, and are thus relatively complex systems, and require periodic maintenance. Hydraulic power assisted steering systems also account for a relatively large proportion of the cost of the vehicle in which they are employed.